Highly stabilized papain conjugated with water‐soluble phospholipid polymer chain having a reacting terminal group

A novel water‐soluble and biocompatible phospholipid polymer, poly(2‐methacryloyloxyethyl phosphorylcholine) (PMPC), was synthesized using a photoinduced living radical polymerization technique for modification of the enzyme. The PMPC had a reactive carboxylic group on a terminal, and its molecular weight and molecular weight distribution were regulated. The PMPC was reacted with the amino groups of papain via amide bonds to form a conjugate (P‐PMPC). The modification degrees with PMPC chains on the conjugate were 22% (P‐PMPC22) and 42% (P‐PMPC42) versus the total number of amino groups of papain. The stability of the P‐PMPC was evaluated in a buffered solution (pH 6.1) at 25 and 40°C. The helix content of the P‐PMPC was slightly below that of native papain. However, the secondary structure of the P‐PMPC was maintained at its initial level for 28 days at both temperatures. The enzymatic activity after the conjugation was about 40% of the native enzyme, but it was maintained about over 75% of the initial enzymatic activity even when it was stored at 40°C for 28 days. This result is due to inhibition of self‐digestion and a change in the ternary structure of papain by the PMPC chains. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 827–832, 2004     

Performance Evaluation of the Hitachi SR8000 Using SPEC OMP2001 Benchmarks

This paper reports the performance of a single node of the Hitachi SR8000 when using SPEC OMP2001 benchmarks. Each processing node of the SR8000 is a shared-memory parallel computer composed of eight scalar processors with pseudo-vector processing feature. We have run the all of the SPEC OMP2001 benchmarks on the SR8000. According to the results of this performance measurement, we found that the SR8000 has good scalability continuing up to 8 processors except for a few benchmark programs. The performance results demonstrate that the SR8000 achieves high performance especially for memory-intensive applications.     

Eigenvalue-based wide area stability monitoring of power systems

Background oscillations are utilized for the real-time stability evaluation of electric power systems. After identifying the parameters of the low-order discrete-time model for the target system from the background oscillations measured at two different locations, the stability of the target system has been evaluated through the eigenvalues of the identified discrete-time model. Real-time simulations have been performed for a longitudinal four-machine infinite-bus system on the Analog Power System Simulator at the Research Laboratory of the Kyushu Electric Power Co. to demonstrate the efficiency of the proposed scheme. The accuracy of the proposed scheme for the real-time stability evaluation has also been clarified through the comparisons with the alternative stability evaluation in the time domain, and also in the frequency domain.     

Study on dependence of AC transport current losses in YBCO‐coated conductors on distribution of critical current density and n value

We measured AC transport current losses in three kinds of thin‐film YBCO‐coated conductors made by different processes. The results showed that the loss characteristics were different and that some of the conductors did not follow the Norris strip model which is generally believed to well explain the loss characteristics of YBCO conductors. In the paper, an analytical model in which distribution of critical current density and n value of the conductor are taken into consideration is proposed to describe the AC transport current loss characteristics more generally than the Norris strip and elliptical models. It is shown that the analytical model explains well the measured loss characteristics of the three kinds of conductors. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(2): 26–38, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20056     

Emergence of higher levels of invasive and metastatic properties in the drug resistant cancer cell lines after the repeated administration of cisplatin in tumor-bearing mice

To establish a more suitable model for reflecting biological aggressiveness in clinically recurrent cancers after chemotherapy, we made the in-vitro-established cisplatin-resistant cell lines, by exposing the parental tumor cell lines to cisplatin in a culture system, and also the in-vivo-established cisplatin-resistant cell lines by repeated cisplatin administration to parental tumor-bearing mice. Although both cell lines similarly demonstrated a clinically relevant low level of drug resistance (from 1.5 to 2.9 times more resistance to cisplatin than their parental cell lines), only the in-vivo-established cisplatin-resistant cell lines showed significantly enhanced metastatic properties with a 2.1- to 3.4-fold increase in the number of lung metastatic nodules. These enhanced metastatic properties were caused by tumor invasiveness in combination with various levels of enhancement of cell attachment, proteolytic enzyme activity and cell motility. We concluded that anticancer drugs such as cisplatin could promote tumor progression only in the drug-resistant cell lines established in vivo. As a result, these cell lines are considered to be a more faithful and useful model for expressing biological aggressiveness in clinically recurrent cancers after chemotherapy than the conventional drug-resistant cell lines established in vitro.     

Large sample approximations for the LR statistic for equality of the smallest eigenvalues of a covariance matrix under elliptical population

This paper is concerned with large sample approximations of the LR statistic for testing the hypothesis that the smallest eigenvalues of a covariance matrix are equal. Under a normal population Lawley [1956. Tests of significance for the latent roots of covariance and correlation matrices. Biometrika 43, 128-136.] and Fujikoshi [1977. An asymptotic expansion for the distributions of the latent roots of the Wishart matrix with multiple population roots. Ann. Inst. Statist. Math. 29, 379-387.] obtained a Bartlett-correction factor and an asymptotic expansion for the LR statistic, respectively, when the sample size is large. In this paper we extend the Bartlett correction factor to an elliptical population. The accuracy of our approximations is examined through simulation experiments.     

Unicast probing techniques for estimation of shared loss rate

The paper introduces two new unicast active end‐to‐end measurement techniques, called the single–double unicast probing (SDUP) and the delay‐based unicast probing (DUP), to estimate the rate of losses which occurs on the shared network path of two flows. A comprehensive performance evaluation and a comparison between these two techniques and an existing one having the same objective, the striped unicast probing (SUP) (Proceedings of the INFOCOM 2001—The IEEE Conference on Computer Communications, No. 2, Anchorage, Alaska, U.S.A., 2001; 915–923), were carried out. We demonstrate that our proposed SDUP technique provides even better estimation accuracy compared to that of the SUP while it requires only one piece of measurement equipment at only one receiver instead of deploying units to both receivers. Furthermore, with only one sender and receiver pair we can measure not only one shared path, but any partial path that begins at the sender and is located on the sender–receiver path. We also show that while the DUP have the same accuracy as the SUP in the case of Drop‐Tail buffer management, the DUP is capable of measuring loss rates of RED buffers, which the other techniques do not work with. The SDUP and the DUP are less intrusive and cause less bursty traffic compared to the SUP. Finally, the adaptation of these techniques into passive measurements is also considered. Copyright © 2006 John Wiley & Sons, Ltd.     

Influence of output power out of a synchronous generator installed in a customer system on current limiting effects due to a fault current limiter

In this paper, it was assumed that a synchronous generator in a customer system was connected to a distribution system via the fault current limiter (FCL). We theoretically investigated the influence of the output power of the generator on the limiting effect of the fault current when a three‐phase short‐circuit fault occurs. It was shown that the fault current out of the customer system, limited by the FCL, rises with the output power of the generator. It was found that the larger the output, the higher the fault current at the fault point is when the limiting resistance is less than 15 Ω in the case of the resistive‐type FCL. On the other hand, the fault current at the fault point decreases with an increase in the output power for a limiting resistance more than 15 Ω. In contrast, it was found that the suppressing effect on the fault current at the fault point due to the inductive‐type FCL hardly depends on the output power. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(3): 15–24, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10357     

A high‐speed reclosing method to improve the stability in a power system

This paper proposes a high‐speed reclosing operating method to improve the stability in a power system. The proposed method calculates the reclosing time, taking a standard case in which the reclosing is not done using the generator phase angle δ, and the angular velocity ω, and the field system voltage ed′. Also, the execution of reclosing time is calculated, while taking into consideration the acceleration/deceleration energy of the generator during a fault. It can be expected that δ is suppressed by this optimum reclosing operation. Therefore, the system stability can be expected to improve by carrying out high‐speed reclosing when a fault occurs. At present, it has been set at a value which seems to be optimal considering various problems in the reclosing time. However, in those methods, the system stability improvement effect cannot be expected. It was demonstrated that the high‐speed reclosing method serves to depress δ in the computer simulation. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 147(2): 13–21, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10317     

Design Methodology and Validity Verification for a Reactive Countermeasure Against EM Attacks

This paper presents a standard-cell-based semiautomatic design methodology for a new conceptual countermeasure against electromagnetic (EM) analysis and fault-injection attacks. The countermeasure, called the EM attack sensor, utilizes LC oscillators that react to variations in the EM field around a cryptographic LSI caused by a microprobe brought near the LSI. A dual-coil sensor architecture with digital calibration based on lookup table programming can prevent various microprobe-based EM attacks that cannot be thwarted by conventional countermeasures. All components of the sensor core are semiautomatically designed by standard electronic design automation tools with a fully digital standard cell library and hence minimum design cost. This sensor can therefore be scaled together with the cryptographic LSI to be protected. The sensor prototype is designed based on the proposed methodology together with a 128-bit-key composite AES processor in 0.18-\(\upmu \hbox {m}\) CMOS with overheads of only 2 % in area, 9 % in power, and 0.2 % in performance, respectively. The countermeasure has been validated against a variety of EM attack scenarios. In particular, some further experimental results are shown for a detailed discussion.